By KEVIN ROOSE

Published: January 14, 2012

The Westlake Chemical Corporation, a manufacturer of raw materials used in plastics, has made an unsolicited all-cash bid to acquire the Georgia Gulf Corporation, a commodity chemicals maker, for $30 a share.

The deal, which values Georgia Gulf at around $1 billion, would create one of the largest manufacturers of olefins, vinyls and other materials used in construction and other industries. It represents a 23 percent premium over Georgia Gulf's stock price, which closed at $24.48 on Thursday.

Westlake first made a $30 per share bid for Georgia Gulf in September, but the chemicals manufacturer, which is based in Atlanta, rejected the offer. It tried again in December, meeting with Georgia Gulf's management to discuss a potential acquisition. But the company ''continued to insist on a standstill arrangement,'' according to Westlake, which made the terms of its offer public on Friday.

''We believe that our proposal represents a unique opportunity to deliver significant and immediate value to Georgia Gulf stockholders,'' Albert Chao, Westlake's chief executive, said in a statement. ''As such, we are surprised and disappointed that Georgia Gulf's management has been unwilling to engage in substantive discussions with us.''

In lieu of a takeover, Westlake has made advances on its target, buying nearly 5 percent of Georgia Gulf's stock. It said Friday that it hoped to meet with Georgia Gulf and its legal and financial advisers ''at any time and in any location'' to discuss its acquisition offer.

''As we have stressed since our initial correspondence in September, we very much prefer to negotiate a transaction with Georgia Gulf, but we have determined that making your stockholders aware of our proposal is necessary,'' Mr. Chao wrote in a letter to Georgia Gulf's board of directors, which was included in the release.